Abstracts

Rationale: Up to 60% of patients with chronic epilepsies suffer from additional psychiatric - predominantly affective disorders. Standardized diagnosis of psychiatric disorders in epilepsy patients is difficult due to different proposals of classification for this diagnostic issue: ICD 10, DSM IV, classification of neuropsychiatric disorders in epilepsy (Krishnamoorthy & Blumer), the latter differentiating major depression (as common comorbidity) from interictal /affective somatoform disorders in epilepsy (interictal dysphoric disorder). Regardless of these different approaches to classifying depression in epilepsy we aimed to demonstrate the potential of VNS in reducing depressive disorders /symptoms beyond its effects on seizures. Methods: Since 2001 we treated 130 patients (female, age 8 to 71,mean 42) with treatment-resistent epilepsies with VNS. 64 (49,2%) additionally showed signs of depression. Diagnosis was established by clinical interview, Beck s Depression Inventory (BDI) and Montgomery Asberg Depression Rating Scale (MADRS). Patients were divided in three subgroups: 1. typical interictal dysphoric disorder 2. major depression (as a comorbidity) 3. depressive symptoms classified axis I disorder in personalitiy disorders (for example cluster B personality disorder, organic personality disorders) Epilepsy syndromes are frontal lobe epilepsy - 29/64 patients, temporal lobe epilepsy -18 patients, symptomatic generalised epilepsy -16 patients and idiopathic generalised epilepsy- 1 patient. Patients were investigated 12-18 months after implantation of VNS, antiepileptic drugs and antidepressants were not modified during this period. Results: Patients were 19-55-years old, 26 of 64 patients (40,6%) had an IDD, 16 patients (25,0%) a major depression, 22 patients (34,4%) had depressive symptoms and personality disorders. Overall 32 patients (50%) responded with seizure reduction > 50%, but in 39 patients (60,9%) showed a significant reduction of depressive symptoms (reduction of scores of BDI and MADRS: > 50%, clinical interview). 9 patients responded with significant reduction of both seizures and depression. Results in subgroup 1 were 14/26 patients 54%/, in subgroup 2 14/16 patients -87%/, in subgroup 12/22 - 54% respectively, differences were significant in Fishers exact test. Conclusions: VNS is effective not only in reducing seizures but maybe even better in different disorders associated with depressive symptoms in epilepsy. In our small group there was an significant trend towards higher effectiveness in major depression . Response in seizure-frequency was a strong predictor of antidepressant effects. But resolution of depressive symptoms seems to be not only a consequence of seizure reduction as significant antidepressive and antiepileptic effects occurred independently, too. This result suggests an independent mode of action of VNS in depressive disorders in epilepsy. Further investigations should be adressed to this question.